Study On Steady-state Hydraulic And Thermal Simulation Of Gas Field Gathering Pipeline Network

When the gas field enters the middle and late stage of production,the production of gas wells decreases.In order to ensure stable production,gas field pressurization projects are increasing.As a result,the structure of pipe network is complicated and the hydrothermal state is complicated and changeable.Therefore,in order to ensure the safe,stable and economic operation of the gathering and transportation network system of large gas fields,it is necessary to provide efficient analysis and evaluation means through steady-state hydro-thermal simulation of the gathering and transportation network.Based on the detailed analysis of the structure of gas field gathering and transportation network,a set of simulation mathematical model of gas field gathering pipeline system is established according to the functions and characteristics of each component in the network.It includes single-phase flow,multi-phase flow,centrifugal compressor,reciprocating compressor and valve.Compared with the common pipe network simulation methods,the linear approximation method,which is fast and insensitive to the initial value of iteration,is used to solve the model.Firstly,based on the characteristics of complex gas field gathering and transportation network topology,this paper analyzes the influence of node numbering on hydraulic calculation of network.A general node numbering sorting method for pipe network containing various equipment components is proposed.It reduces the workload of network raw data preparation and input and improves the program ease of use and automation.Secondly,considering the hydraulic simulation problem of compressor and pipe network matching,the traditional simulation method is extended,and the constraints of the compressor are not limited to the conditions of constant inlet and outlet pressure or constant pressure ratio.The pipe network hydraulic simulation method coupled with the compressor characteristic curve is proposed,and the adjustment of various operating conditions such as variable speed and variable displacement is realized.Thirdly,based on the hydraulic simulation method mentioned above,in order to solve the disadvantage of decoupling the originally coupled single-phase flow of gas gathering network and multi-phase flow of gas production network in traditional gas field simulation,a coupling solution method of gas gathering network and gas production network is proposed in this paper.Finally,a hydro-thermal coupling simulation method suitable for gas field gathering and transportation network is proposed to improve the accuracy of hydro-thermal calculation.Based on the mathematical model of gas field gathering and transportation network and the proposed coupling simulation method,a computer simulation program was developed independently,and three pipes with different topologies were used for verification calculation.Compared with TGNET simulation results,the average relative deviation of node pressure is less than 2%,the average relative deviation of pipeline flow is less than 5%,the average absolute deviation of temperature is less than 3℃,and the calculation time is less than 5s.The results show that the calculation method proposed in this paper can meet the requirements of hydraulic and thermal efficient simulation of complex gathering and transportation network both in accuracy and speed,thus providing a certain reference for the localization of gas field gathering and transportation network simulation software.